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Finding the Fourth Proportional to 76.98, 115.40 and 42.74

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Solution

The fourth proportional to 76.98, 115.40 and 42.74 is: 64.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.98 : 115.40 = 42.74 : x
  2. Step 2: Convert to fraction form
    76.98/115.40 = 42.74/x
  3. Step 3: Cross multiply
    76.98x = 115.40 × 42.74
  4. Step 4: Simplify right side
    76.98x = 4,931.41
  5. Step 5: Solve for x
    x = 4,931.41/76.98
  6. Step 6: Final answer
    x = 64.06

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.